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External SSD disconnects at night w/ error notification about not being ejected properly

I have an external SSD (Samsung 8TB SSD in a Cable Matters Thunderbolt 3 case) that I use for my Photos library.


Recently upgraded to a Mac Studio M2 Max running Ventura 13.5.


It seems like every night, the SSD unmounts, and I come back to an error saying that the SSD was ejected improperly. However, it is plugged in and the drive shows up.


I tried replacing the Thunderbolt cable with a new Thunderbolt 4 cable, no change.


The drive is plugged into one of the 4 rear ports. I do not have this problem with a second SSD plugged into one of the front ports.


I've checked settings to make sure that I don't have it set to put hard drives to sleep. Is there some other setting I am missing? This is a fairly critical problem because putting the drive away this way risks damaging my photo library *and* it gets in the way of my nightly backups.

Mac Studio

Posted on Aug 17, 2023 4:13 PM

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Posted on Sep 1, 2023 9:46 AM

... just wanted to follow up with the solution, in case anyone else searches for this problem.


It turned out the issue was the USB-C cables. Replacing the cable(s) for both external SSDs with new OWC Thunderbolt 4 cables fixed the issue.


This was surprising to me, since the drives and enclosures purchased were high quality and were technically USB 3.1 and/or 3.2 rated. But the cables that came with them seem to have been a source of the instability, where every night they might (or might not) disconnect and then reconnect.


I tried several different cables, but the key seems to have been having Thunderbolt 4 rated cables. My guess is the Mac Studio M2 Pro is somehow just sensitive to this in a way my 2019 iMac was not.

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Question marked as Top-ranking reply

Sep 1, 2023 9:46 AM in response to adamnash

... just wanted to follow up with the solution, in case anyone else searches for this problem.


It turned out the issue was the USB-C cables. Replacing the cable(s) for both external SSDs with new OWC Thunderbolt 4 cables fixed the issue.


This was surprising to me, since the drives and enclosures purchased were high quality and were technically USB 3.1 and/or 3.2 rated. But the cables that came with them seem to have been a source of the instability, where every night they might (or might not) disconnect and then reconnect.


I tried several different cables, but the key seems to have been having Thunderbolt 4 rated cables. My guess is the Mac Studio M2 Pro is somehow just sensitive to this in a way my 2019 iMac was not.

Aug 21, 2023 10:15 AM in response to a brody

So, this did not work. I purchased an OWC Thunderbolt Hub, which is powered, and plugged both SSDs into it. While they mounted, over night, both drives unmounted with the same error. This is after a machine restart, etc.


Something else in the system is causing this. It did not happen previously on my 2019 iMac. Same drives. Same cables. Something in the system config is doing this, but I can't figure out what it is.

Aug 17, 2023 5:27 PM in response to adamnash

Get an AC/DC charged USB hub. Energy Saver does not supply enough power for the ports, and causes problems with disconnects. Your system settings can alleviate it a bit by not putting hard drives to sleep, but that's not a permanent solution. Having a hub with its own power source, or drive with its own power source is a much better solution.

Aug 21, 2023 11:02 AM in response to adamnash

Another alternative would be to just shut down at night and reboot in the morning. Being all solid state a reboot shouldn't take more than 30 seconds, not a big inconvenience. An additional benefit of shutting down each night is that it clears out temporary system and application cache and swap files.


For self powered hubs check out OWC (MacSales.com) which is considered by many here to be the premier 3rd party hardware supplier for Macs. Their Customer Support can point you to a hub that will meet your workflow and budget goals.




Aug 17, 2023 5:36 PM in response to adamnash

The performance should actually improve with a powered hub, because then the power dedication of the computer would be less. I know it seems counterintuitive. Just remember the slowest USB that is connected will slow down everything else on the same bus. The System Profile report in Apple menu -> About This Mac shows you how the buses are dedicated to each USB port as you connect more items to USB. Try the Energy Saver setting. If it continues though then I would definitely get a hub. You don't want to be writing data if it is underpowered anyway, as the file being transfered can get corrupted in transit.

Aug 21, 2023 3:07 PM in response to Old Toad

Possibly, but this was a working set-up until I upgraded to the new Mac Studio M2 Max. This feels like some sort of configuration issue w/ Ventura, but I can't seem to figure out why the machine is dropping the connection at night. I'd really like to just get it back to what has been working for the past year (on an Intel iMac 2019).


On the OWC Hub, already tried that. Didn't work. In fact, possibly worse, because it looks like the drives dropped in the middle of the night and wouldn't re-mount.

Dec 18, 2023 1:02 AM in response to adamnash

Check the firmware of the SSD case. It depends on which kind of chip being used there.


Realtek RTL9210 or Intel JHL7440 or ASM2464, different firmware versions might have different behaviour for power management. Some version might lead to sleep issue causing disconnection.


If using USB-A port, the power output from USB-A port is also a factor to consider.


I ever encountered the issue of disconnection, and resolved by using a USB-C to A(Dual plugs) cable for extra power to SSD case. (2 USB-A ports will be occupied though).

Feb 18, 2024 9:35 AM in response to adamnash

I had the exact same problem. One of my SSD's would keep disconnecting over night when my computer went to sleep. Even though I had set my system settings to do not put drives to sleep. This went on for about 2 months up to the point where it fried my SSD and destroyed it. What I have just done is purchased a powered drive for my main work drive and have that plugged in via the USB A. I then run a 500g NVME SSD-C drive out of the Mac mini M1 and a Sandisk 1TB extreme through a hub out of the 2nd USB A slot. So far after 2 weeks there have been no kick outs of drives. Even when I leave my M1 running overnight, the drives are all attached the next morning. I was running a none powered drive as my main work drive previous to this. Adding the powered drive seems to have fixed the problem. I think the power drain on the M1 was causing the issue.

Feb 26, 2024 8:55 AM in response to a brody

So, I've been having a similar issue with my USB-C portable drive connected to my Macbook Pro 2023 16". When traveling, I use the external drive for my Photos Library and have my library set to download originals to this Mac. I often import photos from an SD card into the library and leave the machine on with the Photos. App open.


I noticed that the external drive ejects after 15-30 minutes, and I get a warning that the drive was disconnected before dismounting.


After testing leaving the drive connected WITH and WITHOUT the Photos app open, it appears that the drive only ejects when Photos.app is open. When it's not open, it doesn't appear to disconnect. However, soon after the app loads, the drive then disconnects, causing the error.


So logic tells me that something Photos is doing something that causes the USB-C portable drive to eject.


I should note when I'm home, I have a duplicate Photos Library on an external 3.5" drive in a powered enclosure and when connected at my home set that library as System Library so that it will sync with all the photos imported when traveling and imported into the library on the external portable drive.


Does anyone experience similar behavior?

External SSD disconnects at night w/ error notification about not being ejected properly

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